This disclosure relates to loudspeaker audio systems having reduced vibration.
A moving diaphragm in an electro-acoustic transducer generates an inertial reaction force on a basket supporting the diaphragm that is transmitted to an enclosure or baffle that partitions a volume into a listening volume and a back volume. The baffle is typically stiff in the plane of the baffle but is susceptible to vibrations perpendicular to the baffle plane. An inertial reaction force having a component perpendicular to the baffle plane can generate a buzzing or an audible noise that detracts from the acoustic signal generated by the electro-acoustic transducer. Although baffle vibration can be problematic at any frequency, baffle vibration may be significant for electro-acoustic transducers generating acoustic signals in a frequency range of less than about 150 Hz, which are commonly referred to as bass speakers or woofers.
U.S. Pat. No. 6,985,593 issued Jan. 10, 2006, U.S. Publication No. US2005/0111673 published May 26, 2005, now U.S. Pat. No. 7,551,749, and U.S. Publication No. US2008/0101646 published May 1, 2008, now U.S. Pat. No. 7,983,436, describe methods and systems for reducing baffle vibrations and are incorporated herein by reference in their entirety. In the described methods and systems, two or more diaphragms are oriented relative to each other such that the net reaction force generated by the two or more diaphragms is preferably zero or less than the reaction force generated by a single diaphragm.